Offensive letters, tearful personal stories and reams of statistics have been shared as plaintiffs' lawyers rested their case Tuesday in a racial profiling lawsuit against an Arizona sheriff and his department.

A woman testifying Thursday at a racial profiling trial against Maricopa County Sheriff Joe Arpaio and his department said that during an unjustified traffic stop a sheriff's deputy slammed her stomach-first into her car while she was five months pregnant.

No longer a backburner issue, immigration is roiling the presidential contest as President Barack Obama and Republican Mitt Romney seek to court the nation's swelling Hispanic population. The outcome could influence political battle lines and shape American politics for generations.

The U.S. Justice Department sued America's self-proclaimed toughest sheriff Thursday, a rare step for the agency after months of negotiations failed to reach a settlement over allegations that his department racially profiled Latinos in his trademark immigration patrols.

A group says it has collected nearly 100,000 online petitions signatures from across the country to demand that federal authorities prove their allegations that Maricopa County Sheriff Joe Arpaio's office has committed a wide range of civil rights violations.